An operating system (OS) is system software that manages computer hardware and software resources, and provides common services for computer programs. General operating systems perform basic tasks, such as recognizing input from the keyboard, sending output to the display screen, keeping track of files and directories on the disk, and controlling peripheral devices such as disk drives and printers.
A computer network operating system, specifically, is a specialized operating system for a network device such as a router, switch, firewall, and so on. For instance, the Internetwork Operating System (IOS) available from Cisco Systems, Inc. is an example computer network operating system, where the IOS software used on routers and switches provides a package of routing, switching, internetworking, and telecommunications functions integrated into a multitasking operating system. For example, a computer network operating system can provide IP routing (basic, IPv4, IPv6, etc.) for data, voice, video, etc., and can provide security services and virtual private network (VPN) services as well as a myriad of other features, such as tunneling protocols, path reservation protocols, connectivity verification protocols, and so on. Generally, computer network operating systems function on various classes of network platforms. Such platforms include routers, switches (e.g., ATM switches, LAN and WAN switches, etc.), file servers, intelligent hubs, personal computers, and any other devices that function within an internetwork.